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I just sent 7 TLOS to you

And regarding your questions, I found this good explanation online:

Your Owner key and Active key can execute the same functions save for one, the Owner key can change the Active key. This means that if your Active key is exposed or changed without your consent you can reset your Active key using your Owner key to do it. This means that your Owner key is the single most sensitive thing you have and should be kept safe. If you are ever required to use your Owner key then it should be immediately reset. Consider it a one-time-use key.